This invention relates to a specialized orthodontic bracket intended primarily for use during early treatment phases on lower (mandibular) first molar teeth, and having a convertible arch-wire buccal tube, a second tube for receiving a lip-bumper wire, and an integral hook which is oriented to minimize occlusal interference and to provide an anchorage for elastics, springs, and similar auxiliary appliances.
Convertible molar brackets have been in use for many years, and reference is made to U.S. Pat. No. 3,391,461 for further background information. Brackets of this type are normally used on younger children whose second molars have not yet grown in, but who have fully erupted first molars which serve as anchor teeth for an orthodontic arch wire. The usual rectangular arch-wire slot is covered by a removable cap to provide a terminal buccal-tube anchorage for the arch wire during early treatment.
When the second molars erupt, these newly emerged teeth are provided with banded brackets which take over the "anchor" function and receive the terminal ends of a longer arch wire. Prior to installation of the longer arch wire, the arch-wire cap on each first-molar bracket is removed to enable normal edgewise treatment of the first molars.
It is also known to provide another buccal tube on such molar brackets to receive a facebow tips for the maxillary arch, and the tips of a lip-bumper appliance for the mandibular arch. The facebow is an appliance which is urged distally (rearwardly in the mouth) by extraoral springs or elastics on a headgear or neckband. The lip bumper is a pad fitted between the lower lip and front lower or mandibular teeth, the pad being secured to an arch wire which extends distally to the molar anchor teeth. Natural pressure from the lower lip on the pad results in a rearward force which urges the first molars distally when this kind of corrective tooth movement is needed.
It is desirable to provide a hook on molar brackets for anchorage of auxiliary appliances such as elastic bands. Known molar brackets of this multifunction type, however, are bulky appliances which present a significant problem of occlusal interference, particularly with respect to positioning and extension of the hook. The machined bracket of this invention overcomes such problems by providing all of these functions, while avoiding occlusal interference with a newly positioned low-profile hook.